I am running three Speedway 9 Super 7 carbs from Speedway ($1,400 in 2014) on my 284 inch engine; chrome plated no less. The end carbs are designed as secondaries with no idle circuits and no choke. The primary carb was delivered with one main jet passage blocked by some sort of casting flaw. It was replaced without charge. The float settings on all three were a mile off; two way low, one high. The floats are nitrile with which you must be very careful in bending the tabs for float adjustment, or you will cause the float to leak and sink. Which I did. I replaced all of the neoprene tipped float valves with with the Grosse ball type valves. I had to replace all of the accelerator pump plungers due to the ones provided becoming swollen and refusing to insert without folding.
I run an 3.5 psi electric fuel pump through the mechanical pump, followed by a regulator and pressure gauge, set to 2.7 psi.
I found the engine to be running too lean, so a rejetted from .045 to .047 and am happy with that mixture. Not a carb quality problem; just tuning.
With all that done, the engine looks beautiful with its chrome carbs and is now running very well, with no fuel or vacuum leaks or further reliability issues.
If I had it to do again, I would forego the chrome and go with the better quality carbs that are available.